public static Cursor FromStream(CursorStream stream)
{
// Create cursor from stream
string path = Path.GetTempFileName();
Save(stream, path);
Cursor retval = Load(path);
File.Delete(path);
return retval;
}
public static CursorStream Create(Image bmp, Point hotSpot, Point backGround)
{
// Convert image to a 256 color cursor stored in a stream
if (bmp.Width > 256 || bmp.Height > 256) throw new ArgumentException("Image too large");
if (hotSpot.X < 0 || hotSpot.X >= bmp.Width ||
hotSpot.Y < 0 || hotSpot.Y >= bmp.Height) throw new ArgumentException("Invalid hot-spot");
if (backGround.X < 0 || backGround.X >= bmp.Width ||
backGround.Y < 0 || backGround.Y >= bmp.Height) throw new ArgumentException("Invalid background");
// Encode to GIF to get 8bpp image
CursorStream cvt = new CursorStream();
bmp.Save(cvt, ImageFormat.Gif);
cvt.Seek(0, SeekOrigin.Begin);
// Then to BMP to get the color table etc.
using (Image bmp8 = Image.FromStream(cvt))
{
cvt = new CursorStream();
bmp8.Save(cvt, ImageFormat.Bmp);
}
// Alrighty, we've got:
// offset 0x0000: BITMAPFILEHEADER
// offset 0x000E: BITMAPINFOHEADER, 40 bytes
// offset 0x0036: color table, 256 x 4 bytes
// offset 0x0436: bitmap bits, stride x height bytes
// Write the .cur file header
CursorStream ret = new CursorStream();
BinaryWriter bw = new BinaryWriter(ret);
bw.Write((short)0); // Reserved, must be zero
bw.Write((short)2); // Type, 2 = cursor
bw.Write((short)1); // Number of images
// Write the .cur image directory
byte width = bmp.Width == 256 ? (byte)0 : (byte)bmp.Width;
byte height = bmp.Height == 256 ? (byte)0 : (byte)bmp.Height;
int stride = 4 * ((bmp.Width + 3) / 4);
int bitStride = 4 * ((width / 8 + 3) / 4);
bw.Write(width);
bw.Write(height);
bw.Write((byte)0); // 0 = 256 colors
bw.Write((byte)0); // Reserved
bw.Write((short)hotSpot.X);
bw.Write((short)hotSpot.Y);
bw.Write(stride * height + 4 * 256 + height * bitStride + 40); // Size of image
bw.Write(0x16); // Offset to image
// Write BITMAPINFOHEADER, we need double the height
cvt.Seek(0x0e, SeekOrigin.Begin);
BinaryReader br = new BinaryReader(cvt);
int tmpi;
byte[] tmpb;
tmpi = br.ReadInt32(); bw.Write(tmpi); // biSize
tmpi = br.ReadInt32(); bw.Write(tmpi); // biWidth
tmpi = br.ReadInt32(); bw.Write(2 * tmpi); // biHeight
tmpb = br.ReadBytes(20); bw.Write(tmpb); // rest of header
int colors = br.ReadInt32(); bw.Write(256);
tmpi = br.ReadInt32(); bw.Write(tmpi);
// Write color table
tmpb = br.ReadBytes(4 * colors);
bw.Write(tmpb);
for (int filler = colors; filler < 256; ++filler) bw.Write((int)0);
// Find out what color the transparency got converted to
cvt.Seek(0x36 + 4 * colors + backGround.Y * stride + backGround.X, SeekOrigin.Begin);
byte transparent = br.ReadByte();
// We'll need the color index of black for the transparency
// Fairly sure that GIF always generates black at index 0, but not 100%
int black;
cvt.Seek(0x36, SeekOrigin.Begin);
for (black = 0; black < colors; ++black)
{
int color = br.ReadInt32();
if ((color & 0xffffff) == 0) break;
}
if (black >= colors) throw new ArgumentException("Converted image is missing black");
// Convert the bitmap bytes. We're building the AND mask as we convert each scan
cvt.Seek(0x36 + 4 * colors, SeekOrigin.Begin);
byte[] andMask = new byte[bitStride * height];
int andIndex;
for (int y = 0; y < height; ++y)
{
andIndex = bitStride * y;
int bit = 0;
for (int x = 0; x < stride; ++x)
{
byte pixel = br.ReadByte();
bw.Write(pixel == transparent ? (byte)black : pixel);
if (pixel != transparent) andMask[andIndex] <<= 1;
else andMask[andIndex] = (byte)((andMask[andIndex] << 1) | 1);
if (++bit % 8 == 0) andIndex++;
}
for (; bit % 8 != 0; ++bit)
andMask[andIndex] <<= 1;
}
// Write the AND mask
bw.Write(andMask, 0, andMask.Length);
// Done!
ret.Seek(0, SeekOrigin.Begin);
return ret;
}
public static void Save(CursorStream stream, string path)
{
// Saves cursor to
using (FileStream fs = new FileStream(path, FileMode.Create, FileAccess.Write))
fs.Write(stream.GetBuffer(), 0, (int)stream.Length);
}
